Driving mechanism



Apr, 24, 1923. l 1,452,570

O. O. NYGAARD DRIVING MECHANISM Original FiledUune l5, 1918l 3 Sheets-Sheet 2 ,3. Egg. 4.

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O. O. NYGAARD DRIVING MECHANISM Original Filed June l5 1918 3 Sheets-Sheet 5 oft-L7: 0.

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OSCAR 0. NYGAAIRD, OF MILTON, MASSACHUSETTS.

DRIVING MECHNISM.

Original application led Jane 15, 1918, Serial No. 240,160. Divided and this application iiled February 25, 1919, Serial No. 279,057. Renewed September 22, 1922. Serial No. 589,994.

` drawings, is a specification, like letters on the drawings representing like parts.

My present invention relates to driving mechanisms, and more particularly to driving mechanisms for use in connection with automatic stokers of the underfeed type,--

though its use is not limited to this class of devices, as it may be used to drive mechanism of any type where it is desired to have a positive. uniform and slow speed drive and one that will automatically disconnect itself from the driven member when the load to be driven exceeds a predetermined amount.

This application is a division of m prior application Serial No. 240,160, file June My present invention contemplates novel and improved means for securing an effective actuating mechanism; means to enable adjustments of various kinds in` the driving devices; simplicity of construction, ease and facility in assembling, and renewin broken or worn parts.

ne of the important Afeatures of my invention consists in the provision of devices associated with my improved driving mechanism, for driving the driven port1ons of' said mechanism at different rates of speed for a constant rate of speed of the drivingl portions thereof.

Another feature relates to the provision of means for automatically disconnecting the driving from the driven portions when the load to be driven exceeds a predetermined amount. v

In the class of apparatus with which the present invention was designed to be used, the work to be performed is extremely heavy, and it was found that the usual form of 59 ratchet and pawl drive was unsuitable, the

sharp end of the pawl continually breaking. To obviate this difficulty a new 'form of ratchet and pawl drive was developed, and.'

a further feature of the invention therefore, is a new and improved pawl and ratchet drive adapted for heavy work.

Referring to the drawings, illustrating preferred embodiments of my invention:

Fi 1 is a cross-sectional viewI through on o the retorts of an automatic underfeed stoker, showing my invention applied thereto:

Fig. 2 is a side View, plartly in cross-section2 of the driving mec anism embodying my lnvention:

Fig. 3 is a plan view of same:

Fig. 4 is an end view:

Fig. 5 is a view in perspective, illting a modification of the driving mechamsm:

Figs. 6, 7 and 8 are detail views of a second modification of the driving mechanism, Fig. 6 being a .plan view, Fig. -7 a sectional side elevation, and Fig. 8 a front elevation:

Fig. 9 is an enlarged ldetail showing the construction of the ratchet and pawl driving mechanism.

In the drawings, 21v designates a ratchet wheel on the shaft 10 and at the point adjacent the wheel 21, is mounted a gear box 24 having a worm and r wheel 25 and 26 receiving power throug a chain 27 from a sprocket wheel 28 mounted on a power shaft 30, which latter is rotated from a source of power, not shown. A similar` gear box 31, sprocket wheel 32 and s rocket chain 33 transmit power from sai shaft 30 to the driving Ameans operatin the ratchet 22 for the clinker pushers. he worm wheel 26 within its gear box is mounted on a shaft 35, which latter runs in suitable bearings 36, 37 within said gear box, and is secured by a key 38 to an eccentric 40. A strap 41 encircling said-eccentric has an upwardly extending arm 42 to which vertical movement is imparted by rotation of the shaft 35 and eccentric 40. The upper part of this arm is provided with a. plurality of holes 43, into a selective one of which is fitted a rod 44 adapted to raise and lift a sliding block 45. Near the upper end of the arm 42 is a recess to receive asteel bushing 46 in which is fitted a shearing pin 47, which latter pin extends either side of the arm and engages a similar steel half round bushing 48 carried by the sliding block 45 to force said block to move downwardl This block has a central aperture slight y flared, as shown in dotted lines in ig. 4, at 49 to permit the rocking action of the arm 42 and its eccentric, edgeways of said arm, while affording aclose sliding fitA to said arm in the crosswise direction where the shearing pin 47 projects and rests on the bushing` 48. This sliding block is provided with a pair of Vertical lugs 50, 51, at opposite'sides mounted to slide in guideways 52 and 53, respectively, formed in posts 54 and 55 extending upwardly from the gear box 24. The sliding block 45 is also provided with a pair of lugs 56 extending forwardlya sufficient distance to straddle the ratchet wheel 21 and supports a pawl 57 on a pin 58 extending between the lugs and constituting a -pivotal bearing for sald pawl. This pawl 57 has its point shaped to engage the teeth on the ratchet wheel 21 and is normally held in engagement therewith by a spring 60. The operation of this driving device will be readily understood on reference to the enlarged detail drawings Figs. 2, 3, and 4. Power being applied to the worm wheel 26 the rotation of the shaft and eccentric carried thereby effects a reciprocating movement in the arm 42, which freely slides through the recess therefor in the center of the block 45, until the -pin 44 strikes said block inthe upward movement of the arm, thereby raising said block and allowing the pawl 57 tov be lifted a distance sufiicient to engage one or more teeth on the ratchet wheel 21 depending on the height to which said block is lifted, and secondly depending upon which one of the holes 43 said rod 44 may be fitted into. This arrangement provides for a considerable range of adjustment, the entire removal of the rod 44 i effecting the stoppage of the driving mechanism and the positioning of said rod in a recess providing for the speed of rotation within the range of one tooth or three teethof the ratchet wheel 21 for each vertical reciprocation of the arm 42. This particular feature of starting and stopping a stoker by simply inserting and withdrawing the lifting pin in my driving gear isof great advantage and one which I desire to claim broad as it enables me to dispose of clutches, brackets, levers, Sprocket-wheel bushings or bearings, and the like; all wearable and expensive parts which require much attention and repairs, and which are universally employed on the primary driving shaft on an prior stoker of the type described. The s iding-block 45 having been lifted upwardlydurin the upstroke of the eccentric and arm 42, t e shearing pin 47 constitutes the -driving connection between the arm and the sliding block, producing a partial rotation of the ratchet wheel 21, depending on the height 'to which said block has been lifted by the rod 44, as just explained. This is the power stroke of the apparatus and moves the crank shaft 10 producing the reciprocation of the fuel feeding rams. In case of any obstruction preventing the proper operation of the stoker, the shearing pin 47 is of suitable size and temper to break before any of the rest of the mechanism will become damaged or injured. By providing the steel bushing 46 holding `the shearing pin in the arm 42-and cooperating steel half bushing in the sliding block, a clean shearing cut is ensured, and a new pin 47 can be easily and instantly applied. Furthermore, this safety factor is in plain view, so that the attendant can see and correct the same at once, without loss of time or danger of damage to the mechanism.

In Fig. 5 I have illustrated a modification wherein the arm 42 is pivotally attached to a slidin member by a bolt 71, the lifting pin 44 eing placed through any one of the oles 43 to lift the cooperating sliding block 72, preferably constituting one-half the sliding member 1n a similar set of guideways to that illustrated at 52 and 53, and already described, and operating the pawl and ratchet to drive the ram and clinker pusher crank shafts. In this construction the shearing is effected by the breaking of the shearing pin passing through the bored recess 74 in the block 2. Other modifications will readily suggest themselves to those skilled in the art.

Referring now to Figs. 6, 7, and 8, the sliding block 45 having the vertical lugs 50 and 51 and the forwardly extending lugs 56, is slidably attached to an upwardly extending link pivotally mounted at its lower end at 81 to the upper end of the arm 42. This link is provided intermediate its ends with three perforations 43, similar to the structures illustrated in Figs. 2, 4, and 5, for the reception of a pin 44. 'Near the upper end of the link 80 is a perforation carrying a steel bushing 82, the hole inwhich is the same size as the hole in a steel bushing 83 in the upper end of a slidable plate 84. The lower end of the slidable plate 84 is bifurcated, as shown in Fig. 7, and fits over a transverse web 85 in the slidin block. A pin 47 passes through the steel ushings 82 and '83, and holds the link 80 and slidable plate 84 in position with relation to each other. The operation of this modification is similar to the other structures already described, in that, assuming the sliding -block 45 to be in the extreme upward position, with the pawl 57 in position to drive the ratchet 21, and the load to be driven by the ratchet being greater than the capacity of the machine, the downward movement of the plate 84 is stopped when the upper face of the bifurcation engages the upper face of the transverse web 85. The link 80 will continue its downward m0vement,resulting` ,pawl 57 to be used; and the circular undercut tooth bottom 92 that allows a strong rounded point pawl 57 to be used and provides a cylindrical bearing surface between ratchet and pawl throughout the stroke. As shown, the point 93 of the pawl 57 is cylindrical in shape, which is of considerable advantage, as the position of the end of the tooth of the pawl with respect to the teeth of the ratchet varies constantly during the movement of the pawl 57 from its uppermost position (shown in dotted lines in Fig. 9) to its lowermost position.

Havingl thus described my invention, what I claim and desire to secureby Letters Patent is l. A pawl and ratchet driving mechanism, consisting in a reciprocable member, a cross-head through which said member slides, adjustable means to effect a lifting of the cross-head, and a driving pin carried by the reciprocable member to eiect a driving of the Ipawl and ratchet equal to the distance said cross-head is lifted.

2. A pawl and ratchet drive, comprising a reciprocating member, a guideway, a crosshead movable in said guideway, and adapted to withstand torsional strain, a pawl carried by said cross-head, a fracturable driving pin between the member and said cross-head adapted to shear under excessive strain, and means to produce a shearing cut on said pin at times of excessive strain.

v3. Driving mechanism, .consisting in a. pawl and ratchet driving connection, a reciprocating member, a cross-head slidably mounted thereon, a pawl pivotally mounted on said cross-head to drive a ratchet, a plurality of steel bushings carried by the reciprocating member and the cross-head, a fracturable pin passing through the bushing in the reciprocating member and engagin the steel bushing in the cross-head, where ythe pin will be fractured and prevent injury to the mechanism if the load driven by the pawl is greater than a predetermined amount.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

OSCAR O. NYGAARD.

Witnees: JAMES R. Holman, RACHEL L. CLARK. 

